Import products and categories with xml file in prestashop

I have installed online computer store with jommla 1.5.12 and virtuemart 1.1.4 but i want to change to prestashop. The project is to import an xml file with all products and categories into prestashop. In the xml file do not have descriptions or images of what we have to get this information through another XML file provided by ICEcat. Xml file categories will not match exactly with the final category of the store. This process must update stock prices once per day. This is the main xml file equema [login to view URL] I've hired 2 programmers and freelancers have not done their job, have not even begun. Of course the 2 I have asked for an advance before starting work. As those who bid for this project to commit to him fully. Do not pay more in advance. Pay 50% of the project to half of the project and the remaining 50% upon completion. Those not agree to these terms please do not offer.